Solidification Process Research On Electron Beam Cladding Of NiCoCrAlY On Inconel 617 Alloy Surface

Inconel617 alloy is widely used in hot-end components of industrial engines.With the development of industry,its high-temperature corrosion resistance and oxidation resistance gradually cannot meet the service requirements of new equipment and product upgrades.However,traditional heat treatment and coating preparation have many limitations,and the use of electron beam cladding technology with unique advantages to prepare protective coatings on its surface has become one of the current preferred methods.However,the solidification process of electron beam cladding can easily cause defects such as surface unevenness,texture,and micro-cracks in the coating.Therefore,studying its solidification behavior is very important to improve the defects of cladding.In this paper,the solidification process of Inconel617 electron beam cladding NiCoCrAlY is numerically simulated,the influence law and importance of different process parameters on the solidification characteristic parameters are analyzed,and the size and distribution of the solidification characteristic parameters under the optimized parameters are studied.shape formation.Secondly,the magnitude and distribution of dynamic thermal stress and residual thermal stress are deeply analyzed,and the influence of solidification characteristic parameters on residual stress is studied.Finally,the solidification behavior of electron beam cladding is summarized by comparing the cladding experiments and the simulation results and correcting each other.The solidification properties simulated via temperature field exhibits that: the self-cooling dominates the solidification of the alloy,the highest temperature of the molten pool is on the surface and the proportion is very low,the solidification characteristics of the edge of the molten pool change regularly with the distance from the surface,resulting in structural structure;the surface fluid-solid impact forms an intermediate Light and dark "U" texture on both sides.At the same time,the penetration depth,maximum temperature,temperature gradient,cooling rate and solidification rate show corresponding regular changes with the process parameters,resulting in corresponding changes in the structure and morphology characteristics.Among them,the scanning speed and the morphology of molten pool are both determined by solidifying speed;the beam spot diameter contribute the greatest impact to the temperature gradient,beam diameter and scanning speed have a similar effect on melt depth.,contrarily,the influence of scanning power is the smallest.The order of influence on the maximum temperature of the melt pool are as follows:beam diameter > scanning speed > scanning power.The molten stress field simulated by the way of the life-death element method indicates that the thermal stress is the smallest at the tail of the melt pool,and diffuses to both sides along the melt channel during the cooling process and increases in value.The surface residual stress tends to increase and then decrease as the distance from the symmetry surface increases,and the maximum is at the edge of the fusion channel.;The combination of the difference in thermal properties of different materials and the large temperature gradient at the bottom of the melt pool results in the highest residual stress in the bonding zone.,and grows and then decreases with distance from the surface.;the maximum residual stress declined significantly with the temperature gradient reduced,and grows dramaticlly as the cooling rate increasing.The analysis results of the cladding experiments show that the surface texture under the simulated optimized parameters is shallow and the residues are less,the molten pool is dense and structurally distributed,the metallurgical bonding is good,and there are no obvious cracks and other defects,resulting in an increase of 499HV0 in the surface hardness compared with the matrix.2.The section hardness shows a slow downward trend.The changing trends of surface topography and penetration depth of different process parameters are basically consistent with the simulation.Through the comparison and correction of simulation and experiment,P=1200w,v=0.008m/s,D=0.005 m process,the surface texture is close to smooth and there is no obvious ablation residue,and the interface metallurgical bond is good and there is no obvious crack and porosity.